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static initialization of extern pointer to function

Alexander Sorockin

Hi All,

Could anybody help me out with the following problem? I have a module with the following declarations.

int (*on_CAN_msg)(void);
	...
void CAN_int_handler(void) interrupt 7 using 1 {
	...

	if (on_CAN_msg)
		on_CAN_msg();
	...
}

Now I have another module:
int CAN_msg_handler(void){
	...
}

extern int (*on_CAN_msg)(void) = CAN_msg_handler;

I also have the following linker's OVERLAY directive to make sure the compiler knows the correct call sequence:
CAN_int_handler ! (CAN_msg_handler),
main ! (on_CAN_msg)

CAN_msg_handler() doesn't get called. However, when I replace extern int (*on_CAN_msg)(void) = CAN_msg_handler;
 with
int main(){
	...
	on_CAN_msg = CAN_msg_handler;
	...
}
everything seems fine. How can I make this code work without having to assign the handler on the fly?

Thanks in advance,
Sandy

Parents
  • 0 in reply to Alexander Sorockin

    Don't worry too much about why your essentially incorrect method miraculously works --- just use the correct one, i.e. the one in which the variable is defined and initialization in the module that has the initializer available to it, rather than the one that wants to call through hat pointer.

    And while you're at it, you should consider getting rid of all 'extern' declarations in .c files. #include header files instead --- that's what they're there for. I.e. there should be a "main.h" contain that extern declaration, and both can.c and main.c should #include that.

Reply
  • 0 in reply to Alexander Sorockin

    Don't worry too much about why your essentially incorrect method miraculously works --- just use the correct one, i.e. the one in which the variable is defined and initialization in the module that has the initializer available to it, rather than the one that wants to call through hat pointer.

    And while you're at it, you should consider getting rid of all 'extern' declarations in .c files. #include header files instead --- that's what they're there for. I.e. there should be a "main.h" contain that extern declaration, and both can.c and main.c should #include that.

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